1. Field of the Invention
The present invention relates to short-range RF networks and, more particularly, to dynamic configuration of nodes in short range RF networks.
2. Description of the Related Art
The availability of various types of communication devices produces a need to have these devices interact with each other in a manner which is cost efficient and which can be easily implemented. Such communication can occur between two or more terminal devices (e.g. telephones, computers, printers, facsimile machines, personal digital assistants (PDAs), etc.) by wired connection such as by connecting electrical conductors to the devices, or by wireless communication using infrared signals or wireless frequency (RF) signals. For many applications, RF signals are preferred as they do not require line-of-sight interaction between a transmitter and a receiver of a terminal device pair.
Recently, low power RF systems have been proposed for providing communications between a plurality of transceivers through a short range link having a broadcast range of several meters. One such local RF system is currently under development and is referred to as “Bluetooth”. This system will be commercially available in the near future and is designed to operate in the open spectrum, (around 2.45 gigahertz). This unlicensed radio band, known as Industrial-Scientific-Medical (ISM) is globally available. The operating range of this RF system is approximately 10 meters for a normal power mode and has proven to be economically efficient. Depending on the available bandwidth in a country (in parts of Europe and the U.S., a bandwidth of 83.5 MHz. is available, which is wider than the available bandwidth in Japan, Spain, and France) either 79 or 23 RF channels are used, the channel separation being 1 MHz. The channel is represented by a pseudo-random hopping sequence through the 79 or 23 RF channels. The hopping is unique in a small area, called a piconet. One of the Bluetooth devices in a piconet functions as master and the others as slaves.
Each channel is further divided into time slots, each 625 microseconds in duration, during which packets can be transmitted by the master and by the slaves. It is planned that Bluetooth chips having the described characteristics will be installed in various kinds of electronic devices for enabling communication among the separate devices. The Bluetooth system will allow for devices such as mobile phones, computers, and other types of terminal devices which are located within an operable range of the RF system to communicate with each other.
Wireless relay networks also exist which, in effect, extend an operating range of a local RF system by utilizing relay devices to interface with and provide communication between two or more terminal devices. Such a network is disclosed in PCT Application No. WO 98/17032 wherein a plurality of communication nodes are wirelessly connected to each other and to a host device for providing numerous communication links for data to be communicated between the host and terminal devices interfaced with the nodes. A drawback of such a system, however, is that it requires manual entry of configuration information when the complement of relay devices is established or altered. This typically requires the presence of a technically trained person. Another drawback of such a system is that a foreign relay device can insinuate itself into a network.
Related U.S. patent application Ser. No. 09/781,190 provides a system comprising a plurality of nodes with the ability to relay from one to another, and provides some automation of network setup. Setting up the network requires every node to page all other nodes, even nodes not within a given node's range, a somewhat complicated procedure. Each node receives a database of information pertaining to all nodes in the network, regardless of whether in range. This is not desirable since databases have proven to be a major source of system problems, and because distributing the node information is a potential security risk. The databases are volatile, so loss of power to a node (as when disconnecting it in order to relocate it, or during a general power failure) requires complete re-initialization.